Organic polymeric materials, such as organic dielectrics, are used in a wide variety of electronic devices, including optoelectronic devices. Examples include transistors, diodes, capacitors (e.g., embedded capacitors), resistors, which can be used in various arrays to form amplifiers, receivers, transmitters, inverters, and oscillators, for example.
Organic semiconductors, such as tetracene, pentacene, and sexithiophene, are currently of great interest for a variety of electronic applications as well. One of the key benefits to using organic semiconductors, versus standard silicon-based materials, is the potential to use solution deposition techniques. However, in order for this benefit to be fully realized, all components of the device should be deposited from solution, including the dielectric layer.
Furthermore, in order to obtain useful devices (e.g., transistors), it is important to have a reasonable charge carrier mobility within the device, preferably greater than 1.0 cm2/V·s. Historically, organic polymer dielectrics have produced devices with low mobilities. However, an advantage of using organic polymer dielectrics is that they are solution processible and photopatternable. Thin layers of organic polymers have been shown to improve mobilities in devices prepared on inorganic oxides, such as Al2O3 or SiO2, which have dielectric constants that are higher than most organic polymers.
A number of organic polymers have been considered as dielectric materials. These include polyimides, parylene C, crosslinked benzocyclobutene, and cyanoethylpullulane. See, for example, C.D. Sheraw et al., “Spin-on polymer gate dielectric for high performance organic thin film transistors”, Materials Research Society Symposium Proceedings v 558, Materials Research Society, Warrendale, PA, USA, pages 403–408 (2000); U.S. Pat. No. 6,265,243 (Katz et al.); and U.S. Pat. No. 5,347,144 (Gamier et al.). Mobilities measured in devices prepared using these polymers, however, are typically no higher than 0.7 cm2/V·s.
In addition, a high dielectric constant is desirable to permit the use of relatively thick films, which have a relatively lower probability of pinhole defects than thin films. Also, a high dielectric constant is desirable to lower the operating voltages of devices while maintaining the same charge polarization.
Thus, organic polymers are desired for a variety of electronic devices (e.g., transistors, capacitors, etc.). Particularly, organic polymers are desired that combine relatively high observed device mobilities with relatively high dielectric constants and that are preferably capable of being solution-deposited, e.g., by spin-coating or similar techniques.